The present invention relates to a method for producing packaging and a corresponding packaging machine. In the method and in the packaging machine, paper material, in particular paper, cardboard or paperboard, is joined by means of an ultrasonic joining process.
In the European patent EP 0 340 334 A2, a device is described which is suited to joining two-ply or multi-ply paper products by means of ultrasound. The paper used in the process is provided with a thermoplastic coating. Longitudinal waves are produced by the sonotrode so that said sonotrode moves towards the anvil and away from the anvil while being ultrasonically vibrated. A sufficient compression of the paper layers is produced here by means of the corresponding ultrasonic frequency and the corresponding contact pressure. At the same time, heat builds up highly in the micro-region of the thermoplastic coating and the paper layers are thus adhesively bound.
In a schematically simplified view, the attached FIG. 10 shows an ultrasonic joining device 100 according to the prior art for joining thermoplastically coated paper material. The device 100 comprises a sonotrode 102 according to the prior art and an anvil 103 according to the prior art. The paper material 5 to be joined is located between the sonotrode 102 and the anvil 103, wherein thermoplastic layers 108 are arranged toward one another. A joining force 106 is applied to the paper material 5 in the gap between sonotrode 102 and anvil 103. The sonotrode 102 executes an ultrasonic vibration in a direction of vibration. In the device 100 according to the prior art, the direction of vibration 107 and the joining force direction 106 are oriented parallel to one another. The longitudinal direction of movement of the sonotrode 102 is thus used here for the joining process.